I am having some what seem to be related problems with any gtk & pango browser.
I'm receiving the following from GDB:
#0 0x0000003cad006fda in pango_fc_font_lock_face () from
/usr/lib64/libpangoft2-1.0.so.0
#1 0x00002aaaba2b8041 in script_engine_init () from
/usr/lib64/pango/1.5.0/modules/pango-thai-fc.so
#2 0x00002aaaba2b7592 in __cxa_pure_virtual () from
/usr/lib64/pango/1.5.0/modules/pango-thai-fc.so
#3 0x00002aaaba2b7e1f in __cxa_pure_virtual () from
/usr/lib64/pango/1.5.0/modules/pango-thai-fc.so
#4 0x0000003cada24b1e in pango_shape () from /usr/lib64/libpango-1.0.so.0
#5 0x0000003cada197dc in pango_layout_set_width () from
/usr/lib64/libpango-1.0.so.0
#6 0x0000003cada1beee in pango_layout_iter_get_char_extents () from
/usr/lib64/libpango-1.0.so.0
#7 0x0000003cada1c40c in pango_layout_iter_get_char_extents () from
/usr/lib64/libpango-1.0.so.0
#8 0x0000003cada1e33e in pango_layout_get_line_count () from
/usr/lib64/libpango-1.0.so.0
If indeed the problem is the same, then a patch is already availablefor pango
(see http://bugzilla.gnome.org/show_bug.cgi?id=411867) which I found as a result
of (http://www.mail-archive.com/desktop-bugs@lists.ubuntu.com/msg67654.html)
To reproduce, attempt browsing to wikipedia and attempt a search for "search
engines". 100% crash rate for me.

I checked the code. Nothing obviously wrong.
Can you attach the mail? To make thunderbird not crash, move the file
/usr/lib/pango/1.5.0/modules/pango-thai-fc.so out of the way temporarily.
Thanks,
Re comment #1, no, this is a separate problem than the upstream bug you link to.